Use of a spoolable compliant guide and coiled tubing to clean up a well

ABSTRACT

Apparatus and methods for cleaning up a well including a coiled tubing inserted inside a spoolable compliant guide wherein well effluents can be flowed through the coiled tubing. It is emphasized that this abstract is provided to comply with the rules requiring an abstract which will allow a searcher or other reader to quickly ascertain the subject matter of the technical disclosure. It is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims.

FIELD OF DISCLOSURE

The present application is generally related to the use of a well intervention vessel to clean up and perform remedial work on an oil and gas well, and more particularly to methods and apparatus associated with the removal of undesired fluids, solid particles and initial flow of an oil and gas well without the need for a costly drilling vessel using coiled tubing and a Spoolable Compliant Guide (SCG). Novel methods and systems to clean up and/or perform remedial and diagnostic work on a well using a combination of coiled tubing, a spoolable compliant guide and a well intervention vessel will be discussed in the present disclosure by ways of several examples that are meant to illustrate the central idea and not to restrict in any way the disclosure.

BACKGROUND OF DISCLOSURE

When a well is drilled and completed it may contain unwanted corrosive or erosive drilling and completion fluids along with solid particles in the wellbore or the near wellbore formation. Most production facilities and production lines are not equipped to handle such fluids and solids and therefore they need to be removed before the well is hooked up to a production line. The removal of such unwanted fluids and solids until the desired proportion of hydrocarbons is produced from the well is referred to in the industry as cleaning a well. The fluids and solid particles may need to be brought to the surface through the wellbore by flowing the well; the effluents are then diverted, separated, processed and stored into a temporary production facility. In a subsea type of well, the temporary production facility is often installed on a costly drilling rig for the purposes of flowing the well until the desired proportion of clean hydrocarbons are produced. At this time the well is considered “clean” and is turned over or hooked up to the permanent production facility or production line. By cleaning up the well from unwanted effluents, the risk of damage to expensive subsea flowlines and associated production facilities is greatly minimized.

It is also possible that the well may not flow as predicted during the clean up process. This could be due to mechanical blockages, equipment malfunction, flow assurance issues, reservoir damage or other potential negative, unplanned events. A drilling vessel/rig often has equipment available onboard to remediate such events but if used, the drilling vessel/rig and its associated access equipment (Subsea test tree, drilling blow out preventer (BOP)/riser, Completion Work Over Riser, etc) will be tied to the well for the duration of the remedial work. As the word indicates, drilling vessels and rigs are designed and primarily equipped to drill wells and the cost of running these types of vessels are very high. Using a drilling rig for remedial or clean up work can negatively impact the economics of a producing field.

When a drilling vessel/rig is used, a rigid tensioned riser and associated heave compensation equipment is needed in order to access the well using a subsurface well package. The above mentioned equipment is needed in the prior art to safely deploy coiled tubing on a pressurized, or at risk of raising pressure, wellbore if a drilling vessel is used. The required use of a rigid tensioned riser and heave compensation equipment comes from the fact that the coiled tubing annular well seal, sometimes called a “stuffing box” or “stripper head”, which is used to keep the pressure contained inside the wellbore, needs to be in close proximity to the injector head to avoid buckling of the coil. The injector head is the mechanical equipment used to drive the coiled tubing up and down the well, due to the properties of the coiled tubing that if the injector head is separated more than a few inches or feet from the annular well seal the coiled tubing will buckle as the coil is pushed down. To have the injector head in close proximity to the annular well seal results in the need to extend the pressurized portion of the well from the subsurface wellhead to the surface where the injector head for the coiled tubing needs to be placed. The way to extend this pressurized wellbore to a drilling vessel is by a rigid tensioned riser, as the vessel is free to move up and down heave compensation equipment will also be required in order to safely rig up and perform a coiled tubing operation.

The cost of using a drilling vessel, a rigid riser and heave compensation equipment typically runs well into the hundreds of thousands of dollars a day, hence a methodology to perform coiled tubing operations without the need of a drilling vessel/rig will result in an improvement for the sake of efficiency and economy.

Such a methodology has been described in an issued patent, U.S. Pat. No. 6,386,290 issued to Colin Stuart Headworth on May 14, 2002, herein incorporated by reference. This patent discloses the use of a Spoolable Compliant Guide to safely and effectively increase the distance from the annular well seal to the injector head from a few inches to hundreds of feet if necessary. The technique uses an annular well seal operatively connected to the top of a lubricator package located in turn at the top of the subsurface well head equipment; the annular well seal is then connected to a Spoolable Compliant Guide that is brought to surface and where the coiled tubing injector head is connected. The SCG serves to connect the injector head to the annular well seal creating a compliant structure that not only replaces the need for heave compensation equipment but also restricts the coiled tubing's movement to prevent the coiled tubing from buckling as it enters the annular well seal.

It is an object of the present disclosure to provide an improved well cleaning apparatus and methods for cleaning up a well that eliminate the need for a drilling vessel to be used during this process.

SUMMARY OF THE DISCLOSURE

The following embodiments provide examples and do not restrict the breath of the disclosure and will describe ways to clean and/or service a well, specifically a subsea well, without the need for a drilling vessel/rig by ways of using a Spoolable Compliant Guide.

The well cleaning apparatus may include coiled tubing inserted inside a spoolable compliant guide wherein well effluents can be flowed through the coiled tubing. The coiled tubing may be fitted with a mating adapter at its downhole end wherein the mating adapter is secured to the subsurface wellhead by securing means. The coiled tubing mating adapter may be a coiled tubing hydraulic rams (RAMs) adapter or any adapter designed to secure the coiled tubing downhole by pairing it with a securing means such as the RAMs of a blow out preventer (BOP) or any other equipment designed to secure the mating adapter. The coiled tubing mating adapter may also be designed for pressure integrity when the securing means is closed around it. The above described well cleaning apparatus may further comprise a flow head attached to the coiled tubing equipment at the surface.

A related embodiment of the well cleaning apparatus includes two annular well seals capable of retaining pressure in the annulus between the coiled tubing and the spoolable compliant guide, wherein the first annular well seal is located in the subsurface wellhead and the second annular well seal is located at the surface. Alternatively the annulus between the outside of the coiled tubing and the inside of the spoolable compliant guide may be pressurized to a pressure equal or greater than the well pressure.

Also a method for cleaning up a well including lowering a coiled tubing inside a spoolable compliant guide and flowing the well through the coiled tubing. The method for cleaning up a well described above may further include a coiled tubing mating adapter fitted on the downhole end of the coiled tubing and securing the coiled tubing mating adapter by activating the securing means over the mating adapter to further flow the well's effluents. Such coiled tubing mating adapter may be a coiled tubing RAMs adapter or any adapter designed to secure the coiled tubing downhole by pairing it with a securing means such as the RAMs of a BOP or any other equipment designed to secure the mating adapter.

The method for cleaning up a well described above may also further include two annular well seals capable of retaining pressure in the annulus between the coiled tubing and the spoolable compliant guide, wherein the first annular well seal is located in the subsurface wellhead and the second annular well seal is located at the surface.

Further, a related method for cleaning up a well includes operatively connecting a spoolable compliant guide at one end to an upper intervention package and the opposite end to a coiled tubing injection head, lowering coiled tubing fitted with a coiled tubing RAMs adapter inside the spoolable compliant guide, positioning the coiled tubing RAMs adapter at the pipe RAMs BOP located in the lower intervention package of a subsea well, closing the pipe RAMs around the coiled tubing RAMs adapter, operatively connecting a flow head to the surface end of the coiled tubing, operatively connecting the flow head to a surface well clean up equipment and flowing the well.

The term securing the coiled tubing mating adapter by securing means refers, by way of example and not to restrict the present disclosure, to closing the BOP RAMs around a coiled tubing RAMs adapter in such a way that the coiled tubing RAMs adapter is unable to move up or down while the RAMs of the BOP are closed. A person skilled in the art will recognize there are multiple means by which a coiled tubing may be secured in a subsurface wellhead equipment by using combinations of coiled tubing mating adapters fitted to the coiled tubing and subs deployed in the wellhead equipment specifically designed as securing means to secure the coiled tubing.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows an example of an embodiment of apparatus used to clean up a well.

FIG. 2 shows detail of equipment used to clean up a well.

FIG. 3 shows detail of the positioning of the coiled tubing RAMs adapter.

FIG. 4 shows equipment set up at surface to clean up the well.

DETAIL DESCRIPTION OF THE DISCLOSURE

In the following detailed description of the preferred embodiments, reference is made to accompanying drawings, which form a part hereof, and within which are shown by way of illustration specific embodiments by which the invention may be practiced. It is to be understood that other embodiments may be utilized and structural changes may be made without departing from the scope of the invention.

The present disclosure seeks to define a novel well clean up and intervention method that eliminates the need to have an expensive drilling vessel/rig and its associated equipment (subsea test tree, landing string, drilling BOP/riser, completion work over riser, etc) in order to perform remedial work, diagnostic work or clean up a well. Further features and advantages of the disclosure will become more readily apparent from the following detailed description when taken in conjunction with the accompanying drawings.

As previously disclosed and a person skilled in the art will agree, most wells will need to be cleaned from unwanted solids and fluids housed within the wellbore and near wellbore formation product of the operations performed in order to complete the well. Unwanted effluents are flowed out of the well before connecting the well to a permanent production facility or production line to reduce damage of such equipment; in most cases the permanent production facilities are ill equipped to handle such effluents. A coiled tubing could provide a safe, efficient to install and retrieve conduit to flow the unwanted effluents; using the technique disclosed in U.S. Pat. No. 6,386,290 issued to Colin Stuart Headworth May 14, 2002, in which a SCG is operatively connected to a annular well seal in one downhole end and the coiled tubing injector head at the opposite upper end, by running a coiled tubing inside the SCG and securing the lower end of the coiled tubing to the downhole subsea intervention package, the well effluents can be then safely flowed to surface for further separation, treatment and storage. All this can be achieved without the need of a drilling vessel/rig and its associated costly equipment because of the compliant nature of the coiled tubing and the SCG.

The inventive apparatus and method may use a coiled tubing mating adapter fitted to the lower end of the coiled tubing that is designed to keep pressure integrity by activating a securing means located in the subsurface wellhead. The coiled tubing mating adapter may be a coiled tubing RAMs adapter and the securing means may be achieved by closing the pipe rams of the subsea intervention package blow out preventer (BOP) over it. Once the pressure integrity is achieved inside the intervention package, the SGC could be used as a secondary safety barrier in case of unplanned rupture of the coiled tubing while offloading the unwanted effluents from the well. A secondary barrier is essential in operations of this type due to the potentially disastrous consequences of a hydrocarbon, corrosive or hazardous fluid spill. As yet another added layer of safety, two annular well seal capable of retaining pressure in the annulus between the coiled tubing and the spoolable compliant guide may be used; the first annular well seal may be located in the subsurface wellhead and the second annular well seal may be located at surface, by applying a pressure equal or greater than the well pressure to the annulus between the coiled tubing and the spoolable compliant guide any possible spill resulting from the premature rupture of the coiled tubing is contained inside the coiled tubing.

The lack of a practical way to deploy a secondary barrier, allowing the operation to be performed without a complex and expensive heave compensating equipment, determining how to increase the distance from the annular well seal to the coiled tubing injector head, determining how to avoid the buckling of the coiled tubing while running it through a remote (i.e. away from the injector) annular well seal and determining how to keep the pressure integrity of a conduit connecting the subsurface wellhead with the surface equipment are problems that have historically forced the industry to use costly drilling vessels/rigs. A person skilled in the art will recognize the herein disclosed techniques offer a novel and a useful approach to allow the use of more economical equipment in order to clean a well.

An example of what one of several possible embodiments of the present well cleaning apparatus may like, from the subsea wellhead up to the surface well clean up equipment, includes: a lower intervention package installed at the top of the subsea tree by means of a hydraulic connector, the lower intervention package may include a lower shear/seal valve, a pipe/slip RAMs BOP fitted with a predetermined size of pipe RAMs needed to preserve pressure integrity when closed around a sub connected to the coiled tubing (‘herein called a coiled tubing RAMs adapter’), and an upper shear/seal valve; a tool trap and a lubricator long enough to house the equipment needed for the operation connected to the lower intervention package; an upper intervention package attached to the top of the lubricator including dynamic seals or annular well seals, a shear/seal Blow Out Preventor and a guide hydraulic connector to operatively connect the Spoolable Compliant Guide. The SCG operatively connects the upper intervention package to the coiled tubing injection head located at surface in the vessel deck, the coiled tubing injector head is used to move the coiled tubing in and out of the well and to maintain pressure integrity in the wellbore. For added safety, a second annular well seal can be rigged up between the Spoolable Compliant Guide and the injector head, providing the means to pressurize the annulus between the coiled tubing and the Spoolable Compliant Guide; by pressurizing the annulus to a pressure equal or greater than the pressure inside the coiled tubing, a positive pressure seal can be generated and in the unplanned event a leak occurs in the coiled tubing, the higher pressure in the annulus will preclude any well effluent from exiting the coiled tubing.

At surface, the well effluents can be diverted to surface clean up equipment by means of a flow head. The flow head may be connected at three preferred places along the coiled tubing; above or below the injector head (after securing and cutting the coiled tubing) and at the end of the coiled tubing while in the coiled tubing drum. The flow head will divert the well effluents to surface clean up equipment. The surface clean up equipment will be configured depending on the needs and equipment availability and a person skilled in the art will understand the wide variation of related equipment that is available and that is not instrumental the present disclosure. The well effluents can be then stored, separated, processed, burned or re-injected as necessary.

An example of a possible variable of the present disclosure is lowering a coiled tubing by means of a coiled tubing injector head rigged up in the deck of a vessel/rig. The coiled tubing is lowered inside the Spoolable Compliant Guide, into the upper intervention package, lubricator and into the lower intervention package. The coiled tubing is fitted on its end with a coiled tubing RAMs adapter acting as a coiled tubing mating adapter and positioned at the pipe RAMs Blow Out Preventer BOP (securing means) of the lower intervention package, the pipe RAMs are of a predetermined size which provides pressure integrity to the annulus above the adapter as it closes around the coiled tubing RAMs adapter. At surface, the coiled tubing is then secured.

In one embodiment the coiled tubing is cut at surface below the injector head, the end is prepared and fitted with a flow head. The flow head is used to divert the well effluents to the surface clean up equipment.

In a separate embodiment the coiled tubing is cut at surface above the injector head, the end is prepared and fitted with a flow head. The flow head is used to divert the well effluents to the surface clean up equipment.

Another embodiment includes a flow head or a choke manifold connected to the end of the coiled tubing as it sist in the coiled tubing reel. The well effluents will then flow from the well through the coiled tubing in the coiled tubing reel and through the flow head or choke manifold to the surface clean up equipment.

FIG. 1 shows an example of what one of several possible embodiments of the present disclosure could look like, from the subsea wellhead up to the surface well clean up equipment laying in a vessel. The equipment may include a lower intervention package 101 installed at the top of the subsea tree, a lubricator package 102 connected to the lower intervention package, an upper intervention package 103 connected on top of the lubricator, a Spoolable Compliant Guide 104 connected to the top of the upper intervention package on the subsurface end and to the surface equipment 105 and a coiled tubing injector head 106 deployed in the vessel deck 107. FIG. 1 also shows a detail of the coiled tubing equipment 108, injector head and coiled tubing reel, and a detail of the surface equipment 109 needed for the clean up operation.

FIG. 2 shows a detailed example of what one of several possible embodiments of the present disclosure may look like, from the subsea wellhead up to the surface well clean up equipment laying in a vessel, the equipment will include a lower intervention package installed at the top of the subsea tree by means of a Subsea tree hydraulic connector 201, the lower intervention package includes a lower shear/seal valve 202, a pipe/slip Rams BOP 203 fitted with a predetermined pipe rams of the size needed to preserve pressure integrity when closed around a sub connected to the coiled tubing, and an upper shear/seal valve 204; a tool trap 206 and a lubricator 207 long enough to house the equipment needed for the operation connected to the lower intervention package by ways of a hydraulic connector 205; an upper intervention package connected on top of the lubricator by means of a hydraulic connector 208, the upper intervention package including a set of dynamic seals 209, a shear/seal BOP 210 and a guide hydraulic connector 211 (EDP) that allows to operatively connect to the Spoolable Compliant Guide 212. FIG. 2 also shows the position of the coiled tubing RAMs adapter 214 that secures the lower end of the coiled tubing 213 and provides pressure integrity to the annulus between the coiled tubing and the SCG.

FIG. 3 shows an example where the coiled tubing mating adapter and the securing means are exemplified in detail by ways of the pipe RAMs of the BOP 301 of the lower intervention package as the securing means, closed around the bottom of the coiled tubing 302 fitted with a coiled tubing RAMs adapter 303 as a coiled tubing mating adapter, designed to keep pressure integrity.

FIG. 4 shows details of an embodiment of one of the possible equipment set ups at surface where the coiled tubing 401 along with the Spoolable Compliant Guide 400 are secured and fitted with a flow head 403 to divert the well's effluents to the surface clean up equipment 402 and storage tanks 404. At the top of the flow head, a pup joint 405 could be rigged up and secured with the traveling blocks as a secondary safety measure in the unlikely event the clamp system used to secure the coiled tubing slips.

The particulars shown herein are by way of example and for purposes of illustrative discussion of the embodiments of the present invention only and are presented in the cause of providing what is believed to be the most useful and readily understood description of the principles and conceptual aspects of the present invention. In this regard, no attempt is made to show structural details of the present invention in more detail than is necessary for the fundamental understanding of the present invention, the description taken with the drawings making apparent to those skilled in the art how the several forms of the present invention may be embodied in practice. Further, like reference numbers and designations in the various drawings indicated like elements.

While the invention is described through the above exemplary embodiments, it will be understood by those of ordinary skill in the art that modification to and variation of the illustrated embodiments may be made without departing from the inventive concepts herein disclosed. Accordingly, the invention should not be viewed as limited except by the scope of the appended claims. 

1. A well cleaning apparatus comprising: coiled tubing; and a spoolable compliant guide; and wherein said coiled tubing is inserted inside said spoolable compliant guide and well effluents can be flowed through said coiled tubing.
 2. A well cleaning apparatus as described in claim 1 further comprising, said coiled tubing fitted with a mating adapter at its downhole end, said mating adapter is secured to the subsurface wellhead by securing means.
 3. A well cleaning apparatus as described in claim 2 wherein said coiled tubing mating adapter is a coiled tubing RAMs adapter and said securing means is the RAMs of a BOP.
 4. A well cleaning apparatus as described in claim 1 further comprising, a flow head attached to the coiled tubing equipment at surface.
 5. A well cleaning apparatus as in claim 2, wherein said coiled tubing matting adapter is designed for pressure integrity when the securing means is closed around it.
 6. A well cleaning apparatus as in claim 1, further comprising two annular well seal capable of retaining pressure in the annulus between the coiled tubing and the spoolable compliant guide, wherein the first said annular well seal is located in the subsurface wellhead and the second said annular well seal is located at surface.
 7. A well cleaning apparatus as in claim 6, wherein the annulus between the outside of the coiled tubing and the inside of the spoolable compliant guide is pressurized to a pressure equal or greater than the well pressure.
 8. A method for cleaning up a well comprising: lowering a coiled tubing inside a spoolable compliant guide; and flowing the well through said coiled tubing.
 9. A method for cleaning up a well as described in claim 8 further comprising a coiled tubing mating adapter fitted on the downhole end of said coiled tubing and securing said coiled tubing mating adapter by securing means to further flow the well's effluents.
 10. A method for cleaning up a well as described in claim 9 wherein said coiled tubing mating adapter is a coiled tubing RAMs adapter and said securing means is the RAMs on a BOP.
 11. A method for cleaning up a well as described in claim 8 further comprising two annular well seals capable of retaining pressure in the annulus between the coiled tubing and the spoolable compliant guide, wherein the first said annular well seal is located in the subsurface wellhead and the second said annular well seal is located at surface.
 12. A method for cleaning up a well comprising: i. Operatively connecting a spoolable compliant guide in one end to an upper intervention package and the opposite end to a coiled tubing injection head, ii. Lowering a coiled tubing fitted with a coiled tubing RAMs adapter inside said spoolable compliant guide, iii. Positioning said coiled tubing RAMs adapter at the pipe RAMs BOP located in the lower intervention package of a subsea well, iv. Closing said pipe RAMs around said coiled tubing RAMs adapter, v. Operatively connecting a flow head to the surface end of the coiled tubing, vi. Operatively connecting the flow head to a surface well clean up equipment; and vii. Flowing the well. 